INFLUENCE OF DEWATERING OF DEEP FOUNDATION ON KEY TRANSPORTATION INFRASTRUCTURES IN SOFT SOIL AREAS OF SHANGHAI

In order to study the influence of engineering construction especially deep foundation excavation and dewatering on key transportation infrastructures in Shanghai, we analyzed relevant engineering monitoring data to investigatethe deformation characteristics of metro tunnels and elevated roads after dewatering of the foundation pits. Also, we combined the change of water level of confined aquifers and layered deformation of soil layers to reveal the influence of dewatering of deep foundation on key transportation infrastructures. The conclusions are as followed:(1)Dewatering of deep foundations contributions to the severe settlement of metro tunnels and elevated roads. The scope of influence can reach 30 times the excavation depth. The settlement rate of metro tunnels and elevated roads decreases greatly after the completion of dewatering, and the rebound of metro tunnels can even be observed. (2)The water level of confined aquifers will undergo significant decrease because of the considerable pumping water volumes. The recharge will also efficiently mitigate the decrease of the water level after dewatering ends. (3)The dewatering of deep foundation will lead to the compression of aquifers and aquitards above. The water release of aquitards is comparatively slow due to their soil characteristics, but the settlement of aquitards is larger than that of the aquifers. The rebound caused by recharge mainly takes place in the aquifers.